Design And Implementation Of Robotic Workstation For Cutting Large Castings With Risers

During the "Fourteenth Five-Year Plan" period,China’s foundry industry focus on green,intelligent direction of development.At present,large castings finishing processing at home and abroad to manual operations,casting quality can not be effectively improved,high-precision finishing technology can not break through the industrial bottleneck,seriously affecting the industrial restructuring and transformation and upgrading strategy to achieve.For the large castings riser cutting robot system key technology research to become the casting industry to high-end direction of development needs,this paper designed a large casting riser cutting robot workstation to achieve automatic cutting of large castings riser.The main research work is as follows:(1)To design a robotic intelligent system that can solve the technical bottleneck in the finishing treatment of large castings’ risers.According to the system hardware design requirements and workflow,the cutting workstation is composed of industrial control machine,industrial robot,flame cutting torch,3D vision system and intelligent control system.Combined with the master-slave control idea,the workstation communication framework is built to realize the communication interconnection between the subsystems under the integrated system and complete the cooperative work between the hardware of the cutting workstation system.(2)Research on 3D vision-based trajectory planning for cutting robots.A multi-point calibration method that solves the hand-eye relationship matrix is used to calibrate the camera according to the characteristics of the fixed field of view of the 3D camera.The point cloud data obtained from the 3D camera sampling is transformed into the point cloud data under the robot coordinate system.A threshold adaptive sampling method is proposed for the point cloud data processing,and a pre-cut spatial curve is fitted using a cubic polynomial.An attitude estimation algorithm is used to complete the calculation of the forward vector and feed vector in the cutting robot operation space by fitting the cutting micro-cutting plane,and the planning results are applied to the robot cutting operation.The cutting path error is within 0.24 mm,and the cutting trajectory is well aligned.(3)Research on friction compensation method based on improved LuGre friction model.Friction compensation for friction in machine manpower position control to improve cutting accuracy.An improved LuGre friction model is proposed for friction compensation,including the steady-state friction force represented by the LuGre friction model,and the position-dependent term related to the velocity.The friction model is identified in steps,and the steady-state friction force parameters are identified using the features of the LuGre friction model,and the position-dependent terms in the model are identified by the SVM multiclass classification algorithm,support vector regression(SVR)and least squares method to solve the system of equations.The error can be reduced by more than 50(4)when the robot is operated under different loads using the improved model and the identification method to calculate the joint friction torque.The friction compensation model based on the improved LuGre friction model plays an important role in improving the cutting accuracy.Through extensive testing and debugging of the cutting workstation at the production site,automated cutting operations were carried out on different large casting risers.The cutting workstation meets the expected design requirements and satisfies the production needs of the relevant factories.The research and design of the robot workstation for cutting large castings’ risers has certain guiding significance for the industry of large castings’ riser finishing.